Radiation Exposure in Computed Tomography

Abstract

Radiation exposures from CT examinations were estimated for four different CT scanners and periods of time in our department. For 12 CT examinations organ doses were calculated using NRPB conversion factors and the effective doses were determined with weighting factors according to ICRP 60. In 1993 radiation exposures per examination using the Somatom Plus were increased compared with those in 1990 using the Somatom 2 because of higher exposure settings and larger scan length. In 1995 using the Somatom Plus S, the effective doses decreased with the introduction of spiral CT examinations but were still higher than in 1990. In 1997 with the Somatom Plus 4 radiation exposures grew again and for some examinations even exceeded the dose levels of 1993. The most important possibilities for reducing radiation exposure in CT are elimination of unnecessary examinations, limitation of the scanned region, reduction of the exposure setting, and increased pitch in spiral CT.